Indirect measurement of tissue analytes through tissue properties

a tissue analyte and indirect measurement technology, applied in the field of biomedical testing, can solve the problems of limited technology state and complex alterations in the measured analytical signal, and achieve the effect of limiting the technology state and improving the accuracy and precision of noninvasive analyte measuremen

Inactive Publication Date: 2006-05-02
GLT ACQUISITION +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0073]Changes in the distribution of water among tissue compartments and other physiological conditions lead to complex alterations in the measured analytical signal. These dynamic changes lead to a biased analyte measurement and have limited the state of the technology. This invention utilizes tissue properties as reflected in key features of the analytical signal to improve the accuracy and precision of the noninvasive analyte measurement.

Problems solved by technology

Changes in the distribution of water among tissue compartments and other physiological conditions lead to complex alterations in the measured analytical signal.
These dynamic changes lead to a biased analyte measurement and have limited the state of the technology.

Method used

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  • Indirect measurement of tissue analytes through tissue properties
  • Indirect measurement of tissue analytes through tissue properties
  • Indirect measurement of tissue analytes through tissue properties

Examples

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third embodiment

where y is the reference glucose concentration. In the third embodiment, when f(·) and g(·) are determined to be linear over the range of measurement, equation #6 reduces to:

ŷ=xpF−(mszG+mi)+b;  (8)

where FεNx1 and GεMx1. In this embodiment, F and G are determined separately as described above using linear methods of calibration. This final realization of the supplemental use of features for glucose measurement is the preferred method.

[0151]In the second category of measurement, the extracted features are used to indirectly measure glucose through:

ŷ=(msg(z)+mi)+b;  (9)

where g: M→1 is a model used to map the features to a variable correlated to the reference glucose level and ms and mi are slope and intercepts used to convert g(z) to the correct units. Determination of g(·) is through an exemplary set (calibration set) of tissue measurements, extracted features and reference glucose concentrations (from blood or interstitial measurements). A sub-set of features is selected based on the...

example 1

Bioimpedance and Bioelectrical Response

[0157]Bioimpedance and bioelectrical response measurements have been clearly demonstrated as an effective means for quantifying the water levels in various compartments of the body [see Siconolfi, supra]. As in the earlier discussion, a bioimpedance or bioelectrical response based meter is used as the apparatus shown in FIG. 2, with the tissue measurement and selected features including intracellular and extracellular fluid levels. The tissue template and related bias measurement are taken from the first bioimpedance tissue measurement of a particular measurement period (e.g., one day). A simple model is constructed via multiple linear regression on a calibration set to relate the two features to the reference glucose concentration. Non-invasive glucose measurement is made by first collecting a tissue template (the first tissue measurement of the day) and associated bias measurement (a single reference glucose concentration determined via an an...

example 2

Near-Infrared Diffuse Reflectance Spectroscopy

[0159]A calibration set of paired data points was collected on a particular subject whose glucose concentration spanned the range 70–350 mg / dL. Each data point included a near-infrared absorbance spectrum of the forearm and a reference glucose concentration determined from a blood draw and analysis. The near-infrared spectra were collected using a custom built scanning near-infrared spectrometer that collected intensity spectra in diffuse reflectance over the wavelength range 1100–1950 nm. The spectral sampling interval was 1 nm and the signal-to-noise ratio at the peak intensity was approximately 90 dB. The detector used in the study was Indium-Gallium-Arsenide (InGaAs) and the optical configuration consisted of a simple fiber-optic interface to the skin with a small (<2 mm) distance between the illumination and detection fibers. Reference spectra were recorded before each sample measurement by scanning an 80% SPECTRALON reflectance mat...

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Abstract

Methods and system for noninvasive determination of tissue analytes utilize tissue properties as reflected in key features of an analytical signal to improve measurement accuracy and precision. Physiological conditions such as changes in water distribution among tissue compartments lead to complex alterations in the measured analytical signal of skin, leading to a biased noninvasive analyte measurement. Changes in the tissue properties are detected by identifying key features in the analytical signal responsive to physiological variations. Conditions not conducive to the noninvasive measurement are detected. Noninvasive measurements that are biased by physiological changes in tissue are compensated. In an alternate embodiment, the analyte is measured indirectly based on natural physiological response of tissue to changes in analyte concentration. A system capable of such measurements is provided.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims benefit of U.S. Provisional Patent Application Ser. Nos. 60 / 382,433, filed May 20, 2002 and 60 / 363,345, filed Mar. 8, 2002; and is a Continuation-in-part of U.S. patent application Ser. No. 10 / 297,736, filed on Oct. 27, 2003, claiming priority from PCT Application No. PCT / US02 / 02288, filed Jan. 25, 2002, which claims benefit of U.S. Provisional Patent Application Ser. No. 60 / 264,431, filed on Jan. 26, 2001.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention generally relates to the field of biomedical testing. More particularly, the present invention relates to methods and apparatus for noninvasive tissue analyte determination.[0004]2. Description of Related ArtNoninvasive Measurement of Glucose[0005]Diabetes is a leading cause of death and disability worldwide and afflicts an estimated sixteen million Americans. Complications of diabetes include heart and kidney disease, blindness, nerve ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): A61B5/00G01N21/27G01N21/31G01N21/33G01N21/35G01N21/65
CPCA61B5/0071A61B5/0075A61B5/14532A61B5/1455A61B5/1495G01N21/274G01N21/359G01N2021/3595G01N21/31G01N21/33G01N21/65A61B2560/0223
Inventor RUCHTI, TIMOTHY L.BLANK, THOMAS B.LORENZ, ALEXANDER D.MONFRE, STEPHEN L.HAZEN, KEVIN H.THENNADIL, SURESH N.
Owner GLT ACQUISITION
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